1. Field
The following description relates to methods and apparatuses relating to metal wiring, and such as, for example, a metal wiring of semiconductor device and a method for manufacturing the same.
2. Description of Related Art
When a metal wiring is formed in a semiconductor device, a digital isolation region is formed with a thick oxide film between a lower metal layer and an upper metal layer for insulation in a region of the semiconductor device where a high voltage of 5,000V or above is applied. The digital isolator region using such an oxide film is usually formed in combination with an adjacent low voltage region.
A general metal wiring of a low voltage region of a semiconductor device is obtained by filling a metal in a VIA hole of an inter-metal dielectric layer having an adequate thickness. The thickness of an inter-metal dielectric layer used in a low voltage region is much greater than the thickness of the digital isolator formed in a high voltage region mentioned above. In addition, in the inter-metal dielectric layer, a metal is filled into a VIA hole in order to form a contact plug. A contact plug is placed between two metal layers, and thus a metal wiring of the semiconductor device comprises a plurality of metal layers and contact plugs that are formed between the plurality of metal layers.
To this end, the process of forming a metal wiring in a conventional semiconductor device requires a process for forming each metal layers and a VIA hole forming process to form each contact plugs.
However, in a case of simultaneously producing a digital isolator and a low voltage region with a metal wiring of a conventional semiconductor, since there is a big difference of thickness between the inter-metal dielectric layer used in a low voltage region and the thickness of the oxide film used in the aforementioned digital isolator, the number of processes required for forming a plurality of metal layers and a plurality of contact plugs increases, thereby increasing the processing costs and decreasing the processing efficiency.